The 543 Mono Compressor delivers the same smooth, musical, dynamic control and brick-wall limiting of the Portico 5043 now in a 500-series format.

The Portico 543 from Rupert Neve Designs is a fully controllable compressor-limiter featuring feed-forward / feedback modes, Peak / RMS detection and a built in side chain high pass filter. There's nothing like a Rupert Neve design matched with a great set of features and the 543 combines that amazing warmth, precision and flexibility that only the Neve name could bring you.

Built around Mr. Rupert Neve’s custom transformer designs, each 543 module encompasses individually controllable threshold, attack, release, makeup gain, ratio, side chain HPF, Feed-Forward / Feed-back selection and Peak/RMS detection modes. With the compressor inactive, the 543 may be used as a transformer-coupled, high-performance line amplifier, and two 543 may be linked for stereo operation as well. The chassis is built to standard 500 series specifications, with power and I/O provided by the rack.

Different Control TypesIn order to control gain, a VCA or Voltage Controlled Amplifier (or Attenuator) is used. There are many types of Voltage Control, including the use of tubes, discrete and integrated solid state circuits and naturally non-linear devices, each one having its characteristic behavior that reflects sonically on the final performance, and gives it a character or signature that can be musically attractive or not! Since the VCA's really have no signature of its own, this compressor has very accurate, low noise, low distortion

A part of the audio signal is rectified and smoothed to produce a suitable control voltage for the VCA which has to respond very quickly and have low distortion. If the response is too fast, low frequency signals will themselves, be gain controlled! If the response is too slow, the signal will overshoot and the first few cycles will not get compressed. The speed and accuracy of the response, known as the “attack”, and the time frame that gain remains under the initial control, known as “release” or “recovery” and plays a large part in the way a compressor sounds.

Switchable ModesThe 543 can switch between feed-forward and feed-back modes. If the VCA Control voltage comes from the 543 output, (after the VCA) it cannot act immediately on the VCA because it has already been modified by settings of the VCA and circuits through which it has passed. This is known as a “Feed-Back” compressor. The two compression characteristics are quite different; there is more “Overshoot” and both the attack and recovery ramps are changed, providing the user with powerful choices.